The ketonization of carboxylic acids is a useful method for the production of dialkyl ketones. For example, the ketonization of acetic acid alone or with other carboxylic acids, esters, and aldehydes is a valuable and high yield method for the production of acetone and other methyl ketones. The ketonization process, however, produces a number of by-products, including a substantial volume of carbon dioxide and smaller amounts of volatile organic compounds (referred to herein as “VOC's”) such as, for example, various olefins, hydrogen, and methane. Emission of these VOC's with the carbon dioxide by-product stream is undesirable from an environmental standpoint. The recovery or destruction of VOC's by absorption/distillation, catalytic combustion, fuel-supplemented incineration, or the like, however, is costly and capital-intensive. An inexpensive method for capturing and reducing the emission of VOC's produced by the ketonization process, therefore, would lessen its environmental impact and improve its usefulness as a means for the production of dialkyl ketones.